Reductive TCA and Acetyl-CoA Pathways Quiz

Which organism group is most associated with the reductive TCA cycle?

• Purple sulfur bacteria

• Deep-sea hydrothermal vent archaea

• Cyanobacteria

• Methanotrophs

What role does succinyl-CoA play in the reductive TCA pathway?

• An electron donor

• An intermediate for 2-oxoglutarate synthesis

• A terminal electron acceptor

• A precursor for pyruvate

What is the electron donor used to reduce fumarate in the reductive TCA pathway?

• NADH

• FADH2

• Ferredoxin

• Hydrogen

What is the end product of the reductive TCA pathway?

• Acetyl-CoA

• Pyruvate

• Glyoxylate

• Oxaloacetate

Which molecule acts as a carboxylation substrate for 2-oxoglutarate synthesis?

• Succinyl-CoA

• Oxaloacetate

• Citrate

• Malate

The reductive TCA cycle is often favored in environments with:

• High oxygen levels

• Low CO2 concentrations

• High hydrogen availability

• Strong light intensity

Which enzyme catalyzes the conversion of citrate to oxaloacetate?

• Citrate lyase

• Malate dehydrogenase

• Fumarase

• Succinyl-CoA synthetase

The reductive TCA pathway is considered evolutionarily:

• Derived from the Calvin cycle

• More ancient than the Calvin cycle

• Specific to photosynthetic organisms

• Inefficient compared to other pathways

Which reducing equivalents drive the reductive TCA cycle?

• NADH and FADH2

• Ferredoxin and NADPH

• FMN and NADH

• F420 and Coenzyme A

What is a significant metabolic advantage of the reductive TCA cycle?

• Low ATP requirements

• High specificity for CO2 fixation

• Independence from reducing power

• Generation of methane